The present disclosure generally relates to a water meter having a flow restricting device having a variable orifice at its outlet to provide back pressure to the flow of water through the meter. More specifically, the present disclosure relates to a water meter that can be used on a fire hydrant and includes a flow restricting device including a variable orifice designed to open and close automatically based upon the water pressure flowing through the orifice.
Presently, water meters are designed to be attached to a fire hydrant to measure the amount of water being discharged from the hydrant. At many construction sites, the fire hydrant is used as a source of water for different purposes. Since the water discharged from the hydrant does not pass water through a meter, specific fire hydrant meters have been developed to measure the amount of water used at the construction site. Typically, the meter is attached directly to the hydrant and the hydrant is opened to supply water to the construction site.
In many cases, the meters are installed and used in a manner in which water is discharged through either a very short hose or without any hose. In these conditions, essentially 0 psi of back pressure is presented to the meter. The abnormally low back pressure can result in abnormally high flow rates relative to the intended flow rates for the meter. The abnormally high flow rate creates over-speeding in the meter, which is a condition in which the meter exceeds its designed flow rate and causes premature wear on the internal components of the meter. Over-speeding can often even cause catastrophic fail of the operating components within the meter.
Presently, different methods have been designed to address the abnormally high flow rates through a hydrant meter. One of these solutions includes a complex and expensive pressure release valve that utilizes multiple moving parts including springs and elastomers. Alternatively, meters have been designed with a small, solid orifice that severely restricts the flow rate of the meter. Each of these solutions includes undesirable properties and thus alternate solutions are desired.